Device to position a communications antenna



April 8,"98 M. i. YouNG v DVICEI TO POSITION A COMMUNICATIONS ANTENNAFiled nec. 29,- 1950` 3 Sheets-Sheet 1 IIHIJHH April 8, 1958 M. P.AYOUNG 2,830,292

DEVICE TO POSITION A COMMUNICATIONS ANTENNA Filed Dec. 29. 195o i ssheets-sheet 2 LIEL, Q

' I/\ V\ W V\ V\ I IIPIIAPEVICEI u WIW \/I UI \/I \/I I (a.) OUTPUT OF lI p' I CLIPPER" m A I I IAP A E CIRCUIT 8 I x (ib) JbL-tz I I l I l I IRECEIVED l I I l l l I l PULsEs l l I I I IMNWMNVW L I OUTP OF I IERNIIII II'VII II IUI wT I I I i i (dII I I i I I I I I I oUTPuToF I aI I Ic II CIGILFIE I )I I I I MI A I II I A I l OUTPUT OI+| |v l PHASE I IDETECTOR 2o 9.l (f) I I 125:5 .IE5- EY swIggH OUTPUTO I *SWITCH-swITOI-Is i I P052 l o |T/l b2 n im) (Cl) OUTPUT'OF DIFFERENTIIT'OR 'I IO p l I Y I (b) UTPU REC(I)II=IERT?IF n o I I ICI J dI LP INVENTORMARVIN P. YOUNG BY ,(Qgi@ MIA/ ATToRNEY yApril 8, 19.58 M. P. YOUNG2,830,292

' DEVICE To POSITION A COMMUNICATIONS ANTENNA Filed nec. 29. 195o ssheets-sheet E INVENTOR MARVI N P. YOUNG f 6. ,fv/9* my] i' AITORNEY5 Qoriginating.

i i 2,830,292 p DEVICE T POSITIN A COMIVIUNICATIONS l ANTENNA Marvin P.Young, Alexandria, Va.

Application December 29, 1950, Serial No. 203,463 Y 1o claims. A(ci.34a-111) i (Granted under Title 35, U. S. C ode (1952), sec.` 266) Thisinvention relates to apparatus for automatically thelrotating searchantenna. The memory is in the form of a continuous pulse train whosetime phase relative to a reference signal corresponds to theroutput ofthe phase shifting device at the instant the burst is received and thusis an indication of the desired bearing of ,thecommunication antenna.This memorized position is then fed into a closed loop phase matchingservo system where the phase of thememorized pulse train is comparedwith the phase of pulses indicating the position of the communicap tionsantenna and from the phase difference thereof` is produced a controlvoltage whichpositionsthecommunn `cations antenna,` in the direction ofthe incoming wave.

Accordingly, one Vobjectlof the 'present invention is to provide a novelsystem for automatically "and quickly United States Patent@ "FCC,

. 2 .v Fig. 4 is a circuit diagram of a novel phase circuit. i v :cFig.`5 shows other waveforms associatedrwith the circuit showninFig. l.

Fig.6 shows various waveforms associatedwith the:

phase detector.v

Referring now more particularly to Fig. 1, a directive communicationsantennaisrcoupled to'asitable selective receiver 8'; which isrtuned. toa desired signalfrequency.

If'the direction from which the `desired'signal is originatingV isnotvshown, without the aid of the present linvention an operator wouldbe required to slowly .rotate the communications antenna 2 about thehorizonlto hunt for the desired signal. The present invention vmakes'such operation nnnecessaryby automaticallyand quicklylposition- Y ingcommunications .antenna 2 inthe direction vof thev desired signal.

A drive motor 3 continuously rotates a directive search y antenna 1which is coupled to the input ofV a frequency selective receiver 7.`A'phase shifting device 5, thercir-x cuit details of which are shownVin Fig. 3, is coupled to the shaft of drive motor 3 and produces -asine wave output the phase of which varies with the position of search.The reference phase is determined'by the.

yantenna 1. phase of, in this instance, a 400 cycle sine wave input tophase shifting device 5 as shown by Vwaveform a of Fig. 2.

By means.` of conventional squaring and peaking cirv cuits 8 which Vclipv-and'pthen` diierentiateA the resulting square wave in the well knownand conventional manner, pulses `are produced having the same phaserespectively as the sine wave output of phase shifting device 5. Waveiform b of Fig. -2 shows these pulses relative to the reference sine waveof waveform a when'the searc'hantcnna has rotated a fraction of arevolution. phase of the successive pulses as shown gradually changingin phase i relative to the beginning of thenearestr sine wave'cyclepositioning a directive communications'antenna in the direction fromwhich aV signal of a ,desired frequency is Another object of the presentinvention is to provide a novelsystem for automatically and accuratelyposition? ing a directive communications antenna Vsolthat it will bedirected in a direction in lwhich a continually rotating directivesearch antenna has received` a burst 'of energy of -a desired frequency.Y j

Another object of the present invention is to provide a novel andaccurate system for positioning a given shaft to a positioncorresponding to the value of given'variable.

indicated by the tmingofa short burst of information.

Another object of the present invention isto provide a phase memorysystem where the phase of a voltage at i any` given instant maybememorized.

`of waveform a. Y p l By means `ofjrectiiier Vdevice 8", the negativediffer-V entiated output from peak'er 8 is eliminated as shown inwaveformb of Fig. 2.

VVThe signals pickedup by search antenna 1. arejfedto l "a frequencyselectivereceiver 7 which isA tunedtotlie desired frequency. Y Receiver8 to which 'communicationsE antenna 2 is coupled is alsotuned to thisfrequency.

A pulse output is produced in the receiver 7 representing the burst ofenergy received shown 'by waveform c of. Fig. 2 when the`directive*response pattern of` Search antenna 1 includes the directionfrom which said desired i irequencyjsignal` is approaching.- By, meansof Ya couventional and well known dilferentiatorA circuit 7' and, y

rectifier 7" a pulse is produced at the leading edge of the receivedenergy which switches a ip iiop switch 9 into a rst switch position.`Switch 9 ispreferably aconventionahan'd wellA known'Eccles-Jordan twoposition stalier 8'( "(pulse Pf of`waveformb inFig. 2) will trigger`These and other objects of thel present invention will 4 become apparentupon the reading of the specication and drawings wherein: 4 i' v Fig. 1is a block diagram of the system of the present invention.

(Fig. l2 shows -various waveforms necessary tothe clear understanding ofthe present invention.

Y. y i Fig. 3 is a circuit diagram of the phase shifting device and 6. ie

Iducedin sy'rnchronism therewith.

bility -trigger crcuit'oftheftype `shown'by circuitV 40 in Fig; 4.@ 'Thenext pulse appearing in the output of rectiswitch9`back toits originalswitch position. When the switch 9 is triggered back into originalswitch position, then by meansofa common and well known'dilere'ntiatorcircuit 10 similar to 7', and rectifier 11, a pulse is pro- (See thevoltage Waveforms a-c of Fig.` 5).. This pulse, asshown in waveform c oflFig.` -5, has a phase Vrelative to the reference frequency measuredbyintervalfb shown in waveform Vb of Fig. Z-andis a measureof thexbearingof the search` 11' antennadirective pattern.-

r'fenfed Apr, ,8. 1958 detecting l Other circuits may be provided toperform the functions of switch 9 such as a one shot (single stability)multivibrator which would open a gate circuit only long enough to allowthe next pulse from peaking circuit 8 to be fed to frequency divider 14.

The problem is now to convert the position of the single pulse shown inwaveform c of Fig. into a series of pulses at the reference frequency(400 pulses per second) having` the .same phase as .the single pulse ofwaveform c. Y

Thecircuit for accomplishingy this result comprises a source of pulsesderived Vfrom oscillator '15 in Fig. 1' having a pulse repetition rategreater than the reference frequency of 400 cycles per second, andafrequency divider 14 which divides by such a factor that the pulses atits output will occur-at a rate of 400 -pulses per second. If oscillator'has a sinusoidal output frequency of 204,800 cyclesper second, andsquaring and peakingcireuit 12 and rectifier 13 convert the sinusoidalIvoltage into pulses having the same repetition rate or frequency, thenfrequency divider 14 must be designed to divide by 51'2 to produce thedesired output of 400 pulses per second..

Such .a frequency divider may be a blocking oscillator frequency dividersuch as disclosed on page 595, volume 19; entitled Waveforms of the M.I. T. Radiation Laboratory series, 1949 edition.

If the pulse shown in waveform c of Fig. 5, which is the pulse producedwhen switch 9 is switched Iback to its original position by the pulsefrom rectifier 8, is used to reset to zero count frequency divider 14(for the. well knownblocking oscillator type divider this meanstriggering the oscillator) then a series of pulses willjfbe producedhaving a pulse repetition rate of. 400 pulses per second which have thesame phase relative to the reference frequency as the last mentionedpulse. The frequency divider 14 must of course only produce a pulse onceevery 512 pulses from zero pulse count position.

The circuit just described ,is thus a phase memory means since the phaseof a single pulse is remembered in the form of a continuous group ofpulses.

To obtainran indication of the position `of the communications` antenna2 so that it can bel compared with, the bearingposition ofthe incomingsignals as indicated by the phase of the pulses from divider14, aphaseshifting device 6 similar to circuit 5 is coupled to the rotatable shaftof the communications .antenna 2. Thephase ofY thesine wave .of voltagein .its output circuit is therefore dependent on the position of theantenna 2. By. means of squaring and peakinglcircuit 19- similar tocircuit 8 and 12, the sine wave isconverted into al group of pulseshaving the same phase. ,Thenby meansof rectifier 19T, al pulse ofa.given polarity is fed tophase l detectorA 20.

Phasedetector 20, the detailsofY which are ,shown in` Fig. 4, produces adirect current voltage. output whose magnitude and polarity areYrespectively'proportional to the magnitude Yand sense of the phasedifference of the 400 pulse trains per second pulses fedthereto frornthefrequency divider. 14 and rectifier 19.

Of course, theremust be an initial adjustment of-thel systemv so thatwhen the search` antenna and communications antenna are stationary andfacing in thefsarne direction, the phaseof the pulses produced bytheirlassociated circuits produces zero output-in the phase detector 20. Forthe circuit shown in Fig. 4, condition of zero output occurs whenpulsesfed to the phase detec tor 20 by divider 14 and peaker 19 areISO-degreeszout of phase, Thus, referring to waveforms d-f. of'Fig. 2,the phase of thepulses-shown in thej-left portion ofwaveforrndrepresenta condition where thedirectionof the directive patternof the:communications antenna andthe direction of the incoming signal areidentical so that the pulses-shownin waveform fe, whichiare thel pulsesat,l the outputfof lrectiiier 19', are "180' `degrees` out of phaseVdetector 20 is zero as shown by the left portion of Wavelform f.

The phase of the last three pulses shown in waveform d represent acondition where the bearing of the cornmunications antenna 2 is notpointing in the direction of the incoming signal and accordingly thephase of these pulses are not 180 degrees out of phase with the pulsesshown in waveform e kbut lag by an amount c from this condition. A netvoltage appears in the output of phase detector 20 as shown by the solidline in the right portion of waveform f. g

if the pulse output of frequency divider 14 shown in waveform wereleading the 180 out of phase condi,- tion by an amount c then the dottedcurve in the right hand portion of waveform f would represent the outputof the phase detector 29.

Assuming'moor 4 is a two phase alternating current motor, the directcurrent voltage output of the phase detector must beconverted to asuitable alternating current lvoltage such as 60 cycles per second bymeans of a vibrator 21. The vibrator comprises a vibrating contact 26which by means of the 60 cycle alternating current flow in vibratingwinding 27 is caused to intermittently make contact with terminal 2S andground terminal' 29. (This rate will be ,60 cycles if vibrating element26 is polarized.) Terminal 28 is coupled to the output of the. phasedetector 20.

For the solid Curve of waveform f of Fig. 2 representing the directycurrent output of the phase detector 20 for a given phasev condition, asquare wave of voltage at the 60 cycle rate varying between a positivevalue and. ground potential (see the solid curves in Fig. l) will be fedto a conventional amplifier 22 which in -turn feeds an alternatingcurrent voltage of a given phase t0 motor 4 in amanner well known in theart. Amplier 22 is made to have alow frequency response so that thesquare wave input is converted to a sinusoidal voltage at its output. Y

If the output of the phase detector were the dottedv line curveofwaveform f of Fig. 2, then the square wave ofvoltage -will belSO-degrees out of phase with the previouslymentioned phase conditionand will vary between. as given negative value and ground potential.(See-l dotted curvesin Fig. l.) The voltage fed to drive-motor 4 willtherefore be 180 out of phase with the voltage fed thereto when thevoltage output of the phase detector was .that shown by the solid linein waveform fandv will therefore. rotate motor 4 in the oppositedirection untilthe output of thephase detector is zero. Thenthetherewith. Accordingly, the voltage output1 fy the phase-'75communicationsy antenna .2 is properly positioned lto receive theincomingrsignal.

The circuit details of one suitable phase shifting1 means 5 or6 is.shown in.Fig..3-. The circuit in the form illustratedcomprisesatransforrner 30 having a rotatable primary 31, which'isv.coupled to the shaft of the associated rotatableY antenna 1 .or 2, anda delta or wye connected secondary 33. Connected to the three terminalsof the secondary 33 are respective resistors 34, 35 and 36. Resistances3 4 and. 35 are made equal and resistance 36 ismadejabout 30 percent ofthe value of resistance34 or 35.V A series circuit4 of a, condenser 37and a resistance 38 are placed across two of the secondary terminals..If the impedance of the condenser and the value of resistancey 38 aremade equal at the operating frequency l(400 cycles) then as the primary31 is gradually rotated throughout one revolution the phase of thevoltage acrossrpoints x andry of Fig. 3 will gradually beshifted'through 360 degrees relative to the reference .frequency whichis fed to the primary winding 31 through slip rings 32.

If Vthe primary is rotated at a rate of l revolntionper nonlconductivecondition.

which is symmetricall about ground potential.

assumingthaf the 'vonage fed to the "primary s1 is a 40o cycle sinewave.)

Figure 4 shows an example; of a circuit for phase de-v tector 20 whichis also disclosed in the copending application of D. H. Gridley, SerialNo. 199,907, led

q December 8, l 1-950.

in a non-conductive` condition. Likewise, if a positivev pulse is fed tothe grid of right tube 42, the latter tube will be rendered conductiveand tube 41 will be in a A'Ihevolta'ge at lthe'output of tube 41 is fedto a circuit including condenser 51, and a parallel circuit includingresistance 50 in parallel withcthe parallel diode circuit 60.\Diodecircuit` 60 includes .two diodes. 45` and 46 connected in opposedcircuit relation so that only one diode is conductive at anyone time.Resistors 43 and 44 are ``respectivelyin series with the diode 45 and4'6. A'condenser 48 is connected to the cathode of diode 45 and acondenser 49is connected to the plate of diode 46. Potentiometer 47isconnected between the cathode of diode 45` andthe plateof-diode 46.` Theoutput is taken between' the mid-point of potentiometer 47 which isconnectedfto `output terminal 52 and ground terminalV 53. The circuit ismade symmetrical in the sense that resistors'43and 44,and:condens`ersi48 and 49 are respectively made equal in value. i A

Due to the fact that the time constant of the condenser diode chargepaths are equal, the voltage developed across condenser 51 is theaverage value of the voltage on the plate of switch tube 41. Thus, ifthe pulses fed to the respective grids of tubes 41 and 42 are 180degrees out of phase then waveform a of Fig. 6 shows the voltage developed across resistance 50. A square wave `results The voltageto whichtheicondenser 48 charges, due to the heavy conduction -of diode 45 isthe amplitude p of the positive goingportion/ of the square `Wave ofvvoltage shown in Waveforma. Accordingly,the voltage to which condens- Yer 49 charges is the amplitude of the negative going por- 1 `tion n ofthe said' square wave. The average value of the `.voltage on condensers48 and49 are respectively proportional to -the positive and negativeIamplitude p and n of. the square wave of voltage across resistance 50.The

therefore zero for a symmetrical voltage wave.

From what has been said, if the pulses fed to the phase detectingcircuit differ in phase from 180 degrees so as to produce a .square waveof voltage across resistance 50 as shown by waveform b of- Fig. 6,'thenthe average voltage .at theoutput of terminals 52 and 53 will be a netpositive fvalne. Y

If waveform c of Fig. 6` is the voltage across resistance 50, thenftheaverage voltage at the output ofthe phase detector circuit will be Ianegative value. v p

It should be noted that a drift of frequency of oscillator 15 wouldetect the accuracy of the system. This inaccuracy is eliminatedbyaddition of a frequency divifd'erf 16 of a suitable htype suchas arewell known in the art to provideVJ the 400 cycle sinusoidal referencevoltage used to feed phase shifting devices and 6. Thus any shift inoscillator frequency would cause a corresponding shift in the pulserepetition rate of the pulse fed to phase detector 20.

Itusliould be understood` that many modifications may be.` made. ofthespecific embodiments disclosed without deviating from the scope of thepresent invention.

The invention described herein may be manufactured and kused by or forthe. Government of the United States ofAmerica for governmental purposeswithout the payment of anyroyalties thereon or therefor.

i voltage.: developed at the`output of terminals 52 and 53 is What isclaimed is:

1. YApparatus for automatically .positioning a rotatable? directivecommunications antenna lin a direction in which a continuously rotateddirective search antenna has re-V ceived signals of a. given frequencycomprising the corn-v bination of a first means for producing a voltagehaving4 a phase which varies in proportion to the position of saidsearch antenna, second means coupled to said searchA antenna forselectively receiving signals of saidfgiven frel" quency, third meansresponsive to the burst of energyin the outputmof said second means toprovide a voltageV which is substantially in phase with the voltageoutput of said Yfirstrneans at the time said signal of said given tfrequencyA is received, fourth means for producing a volt-4 age having aphase proportional to theV position ofV said communica-tions antenna,means including a phase detectingcircuit coupled to the output of saidthird and fourth means for comparing the phase of the voltageproducedthereby and for moving said communicationsantenna in a directionsuch as to maintain a given predetermined phase relation between saidcompared voltages.

2. Apparatus for automatically positioning -a rotatable directivecommunications antenna in a direction in'which a continuously rotateddirective search antenna has received signals of a -given frequencycomprising the com bination of a rst'rneans for producing voltage pulsesburstof energy in the output thereof by being triggered only into afirst switch position, third means coupling the output of said iirstmeans to said switch meansffor triggering same only into a second switchposition, fourth l means for producing pulses of a given pulserepetition rate f1 having'a phase proportional to the position of saidcommunications antenna, a source of pulses haviiigf Y a pulse repetitionrate f2 which is a multiple of f1', pulse counting meanscoupled to saidsource of pulses operative 'A to produce anoutput pulse every pulsecounts, fifth means coupled `between said switch means and said pulsecounting meansA for developing a voltage pulse substantially` insynchronism with the trgv gering of said switch means. to said secondswitch position for .resetting said pulse count means to zero countposition in substantial synchronism therewith, and means including aphase detecting means coupled to the output of said. fourth means andsaid pulse count means for comparing the phases of the voltage pulsesproduced therein and for moving said communications antenna in adirection such as to maintain a given predetermined phase relationbetween said compared voltage pulses.

3. Apparatus for automatically positioning a rotatable directivecommunications antenna in a directionv in which a continuously rotateddirective search antenna has received signals of a given frequencycomprising the combination lof a first means for producing volt-agepulses having a phase which varies in `proportion to theposition ofrsaidsearch antenna, second' means coupled to said search antenna forselectively -receiving signals1 of said given frequency, third meanscoupled to the output Iof said rst means and to said second meansresponsive to the burst of energy in the output of said second means byproviding a pulse which is substantially in synchronism -With the pulsein the output of said first means which r'st occurs after'said burst ofenergy is received, fourth means for producing pulses of a givenV pulserepetition rate f1 having a phase proportionaltothey position of saidcommunications antenna, a source of pulses 'having `a pulserrepetitionrate 'f2 which is a multiple'of f1, pulse 7i counting means coupled tosaid source,of -.pl1lse sopera tivetdproducesannuitputpulsetevery tionrepresented'bythe time occurrence of an .energy pulse comprising` afirst means foroprovifding said energy pulse, second means for providingavoltage which is continually changing in phase at apredetermined rate,third means responsive to said energy pulse to provide a voltage whichis in phase with the voltage output of. said second means at the timesaid energyk pulse occurs, fourthmeans for providing a voltage having aphaserproportionalejto .the

position of said rotatable shaft, means including a phase t detectingmeans coupled to the output. of said third and fourth means forcomparing the phase of the voltagesrproduced thereby and for.movingsaidrotatable shaft 'in a direction to maintain a givenpredetermined phase yrelationfbetween said compared voltages. Y

5. A system for positioning a given device to aposition representinginformation-,given in the `form of -the time .occurrence ,of a givenenergy pulse comprisingarst means for providing said' given energypulse, Second means for providing voltage pulses whichV are continuallychanging in phase, third means coupled to theoutput of said first andsecond means for delivering a voltage,pulse which is substantially insynchronism with the pulsein the output of said second means which-firstoccursafter-.the occurrence of said given energy pulse, fourth. meanscoupled to said given device for providing voltage pulses of a givenpulse repetition rate f1 having a phase proportional to the position ofsaid given device, a source of pulses having a pulse repetition rate f2which is a multiple of f1, pulse counting means coupled .to-said sourceof pulses operative to produce an outputevery pulse counts, fifth meansAcoupling Ythe output of said third means to said counting means forArendering same operative to count from zero count position insubstantial synchronism therewith, means including a phase detectingmeans coupledto the output lof said pulse count means and said fourthmeans for comparing the phase of the kpulses produced thereby and formoving said given device in-a direction to maintain a givenpredetermined phase relation between saidcornpared pulses.

`6. A system for positioning a given device to a position representinginformation given in the form of the time-occurrenceofa given energypulse comprisinga rst means for providing said given energy pulse,second means forlproviding voltagepulses which-are continually changingin phase, switch means coupled to the output of said first meansresponsive tothe pulses iu the output thereof lay-being triggered-onlyinto a first switch position, third means couplingytheoutputfofsaidsecond means to ,said switch meansfor triggering-:same only into asecond switch position, fourth means coupled to said lgiven device forproducing pulses or" agiven pulse repetition rate f1 having a phaseproportional to the` position of said device, a

sourceof pulses having a pulse repetition-,rate fz which is a multipleof fi, pulse counting means coupled to; said 8v source `of pulsesoperative to producean output pulse every f1 pulse counts, fth meanscoupled between said switch means and said pulse counting means fordevelopingv a voltage pulse in substantial synchronism-with thetriggering of said switch means into the second switch positionl forrendering said pulse counting means operative to count from zero countposition in substantial synchronism therewith, means including a phasedetecting means coupled to the output of said fourth means and saidcount pulse means for comparing the phase of the pulsesproduced therebyand for moving said given dev ice in Ia direction to maintain a givenpredetermined phase relation between said compared pulses.

7. A circuit for indicating the time occurrence of a given energy pulsewithin a given recurrentvtime interval of t1 seconds by the phase of arecurrent group of pulses. comprising a irst means for producinga--group of pulses whose phase relative to a given frequency f1isfperiodically varied over a given range each t1 seconds, aswitch meanshaving only two switch positions, a second means coupling said givenenergy pulse to said switch means for triggering same only into a rstgiven switch position, third means coupling said group of pulses of saidrst means to said switch means for triggering same only into a secondswitch position, a source of pulses having a pulse repetition rate f2which is a multiple of f1, apulse counting means coupled to said sourceof pulses operative to produce an output pulse every pulse counts,fourth means coupled between said switch means and said counting meansfor developiuga voltage. f

pulse in synchronism with the triggering of said switch means to saidsecond switch position for .resetting said pulse counting means intozero pulse count position fin synchronism therewith, whereby the phaseof thepulses produced at the output of said pulse count'meansindicatesthe time occurrence ofV said given energy pulse.

8. The combination of a rst means forproviding a pulse of energy whichvaries in phase relative .to a given. frequency f1 to represent agivenquantity of information, f

a source of pulses havingta pulse-repetitionrate f3 which is a multipleof f1, frequency divider meansfcoupled to said source of pulses forproducing apulseevery pulse counts, means coupledbetween theoutputofsaidfirst means and said pulse .counting meansffor resetting said pulsecounting means Vto zero vcount position in rsynchronism with said pulseof energy.

lt).l The combination of a rst means for` providing .-a, pulse of energywhich varies in phase relative to agiven frequency f1 to represent agiven. quantity of V informacounts, means coupling the pulses at theoutput of said first means to said counting means for rendering saidcounter operative to count from zero count position in synchronism withsaid pulses of energy.

, 10 References Clted'in the tile of this patent UNITED STATES PATENTSGossel Mar. 11, 1941 Williams Sept. 30, 1941 VAyres Aug. 31, 1948McLamore et al Nov. 15, 1949 Woodward Sept. 19, 1950 Lancor et a1. May1, 1951

